Centrifugal compressor



May 28, 1946. w. VAN RIJSWIJK CENTRIFUGAL COMPRESSOR Filed Sept. 14, 1943 Patented May 28, 19,46.

2,461,206 a f UCENTRIFUGAL COMPRESSOR l Wlllem yanRijswij k, Baden. Switzerland, assign I g e ortoAktlengesellschaftBrown, Boverl & Ole, 1 Baden. Switzerland a V i Application September 14, 1943, Serial No. 502,333 n Switzerland Augustin 1242 (019230-434) l n i before the blades are riveted; this impeller they for instance be of thecast type with a centrally apertured forward shroud seating against the inside of'the cover plate I whilst the rear shroud 1 is in contact with the hub disc 2, the impeller being centred on this latter disc. The hubdisc 2 has the usual cylindrical hub 2 for mounting N -45ers 8 Claims. 7

Sometimes it is desired that the impellers of centrifugal compressors should have skewed blades. This, however, meets with certain diiiiculties, especially with impellers ,having high peripheral velocities where for reason of safety cast wheels cannot be used, because the usual method of fixing the blades by means of rivets -EM we together by way of an impeller; and

.tions.

milled out of the blades can no longer be employed in this case. i

It has already been attempted to avoid skewing the blades by arranging an additional impeller with axial blading in front of the main impeller or by inserting such an additional wheel with partial axial blading which becomes radial towards the outlet into the inlet opening of the main impeller. Both methods have, however, the disadvantage that the blades of the additional impeller obstruct the inlet opening of the main impeller too much.

The present invention concerns an impeller for a centrifugal compressor whose blading is skewed at the inlet, but afterwards is axially cylindrical.

The novel feature of the invention is that the impeller consists of a main impeller comprising a hub disc and a cover disc and an additional impeller with skewed blades which is located inside the main impeller and has a diameter larger than that of the inlet opening of the main impeller. One method of making this combined impeller is to locate and fix the additional impeller inside the main impeller before this latter is finally assembled so that the additional impeller is accurately centred, whereupon the hub disc and cover disc of the main impeller are connected of the blades of the main impeller and the inserted additional impeller.

constructional examples of'impellers embodying the invention are shown in the accompanying drawing in which: i

Fig. l is an axial section through the upper half Figs. 2.and 3 are fragmentary end elevations,

with parts in section as taken approximately on line A-A of Fig. l, of relations between the impellers having dilferent blades of the impeller see-- In the drawing, the reference numeral I indicatesthe cover disc having a central opening, 2 the hub disc and 3 the blades which are connected to the discs I and 2 by meansof rivets 4. These blades arenaxial-cylindrical and generally curved and they form the usual annular assembly of impeller blading. The additional or part impeller 5 which is built into the space radially inward of the blade assembly 01' the main wheel nular space between the inner edge of thecover of the inlet passage.

disc I and cover disc 2 in such a disc I and the hub 2' 6, 1 are rounded off to form a smooth extension The impeller 5 is preferably 2' of the main impeller before the cover plate I is brought into position, and is keyed to the main impeller by pins or rivets 8. Under certain conditions, it is sufficient if the additional impeller is clamped between the hub manner that centered on the hub relative displacement is impossible.

The blades of the wheel 5 are manufactured,

with the desired skewed form and their outlet edge either coincides exactly with the inlet edge of theblades 3 or at least part of the former are displaced more or less with regard to these latter blades. The main impeller can have the same or a different number of blades as the additional impeller. In the latter case it is expedient to give the main impeller more blades than the additional impeller. The radial gap 9 between the impeller 5 and the blades 3 can be made as nar ends of the blades 5 of the additional impeller row or as wide as desirable.

If the combined impeller is constructed, as shown in Fig.2, in such a manner that the outer exactly coincide with the inlet edges of the-external blades 3 of the riveted main impeller, then uninterrupted impeller channels are formed whichare boundedat the, entrance by skewed blades and at the outer part by axial-cylindrical blades. This design is often preferred to the one where the additional impeller has fewer blades,

see Fig. 3, than the main impeller or where there is a gap between both kinds of bladeabecause a. i very good conductance of the medium which is i to be compressed is obtained.

Iclaim: l 1. An impeller for a centrifugal compressor,

; said impeller comprising a hub disk, a cover disk.

a plurality of main impeller blades in an annular assembly between said disks, saiddisks and blades having cooperating means for securing said is the axially extending I inlet passage I, and the inner edges of the shrouds blades to said disks, and an additional impeller located within said annular assembly of impeller blades and secured between said disks, said additional impeller and hub diskhaving cooperating parts for centering said additional impeller with respect to said blades.

2. A centrifugal compressor impeller having skewed blading, said impeller comprising the combination with a hub disk, a cover disk having a central opening, and axially cylindrical bladesse- ,cured between said disks to forms. main impeller having an axially arranged inlet passage; of an additional impeller with skewed blades located inside of and secured to said main impeller, the additional impeller having a diameter larger than that of said inlet. r

3. A centrifugal compressor impeller as recited in claim 2, vwherein the blades of the additional impeller at least partly connect up with the blades of the main impeller.

\in'claim 2, wherein the additional impeller is of the cast type. i

8. A centrifugal compressor impeller as recited in claim 2, wherein the main impeller and the additional impeller have the same number of blades, and the outer edges of the blades of the additional impeller aline with the inlet edges of the blades of the main impeller.

WILLEM VAN RIJSWIJK. 

